Neil Jordan’s “Byzantium” dares to rework “Twilight” with twice the teen moping and Robert Pattinson replaced by a guy with the sexual magnetism of a sickly Ron Weasley.

Saoirse Ronan and Gemma Arterton play feuding mother-and-daughter vampires who roam Britain murdering losers and twerps for their blood, as they have done for 200 years. The movie’s idea of a big twist on the legend is that they use their pointy thumbnails instead of fangs.

In a series of increasingly tiresome visits to the early 19th century, with flashbacks nestling within flashbacks, we gradually learn the convoluted tale of how the prostitute Clara (Arterton) gave up Eleanor (Ronan) for adoption after an encounter with an evil sailor (Jonny Lee Miller) and a kindly one (Sam Riley). Meanwhile, in the present, Eleanor tiptoes into an unconvincing love affair with a geeky leukemia sufferer (Caleb Landry Jones) as her equally clueless teacher (Tom Hollander) does some mild sleuthing that seems unlikely to lead anywhere. When the two stories finally join up in the closing minutes, it’s far too late to care and the resolution is hasty.

Ronan, who has all the warmth and looseness of porcelain, weighs this familiar story down with her droopy despondency. She, and the movie, need a blood transfusion.